Guns

ntroduction to How Revolvers Work 2. Gun Basics and History 3. The Revolver 4. Lots More Information

In 1830, when he was only 16, Samuel Colt left home and took a job on a merchant ship bound for India. In his spare time, he toyed with designs for a new sort of gun -- one that could be fired repeatedly without reloading. While a number of repeating weapons had already been developed, none of them had caught on with the public, mostly because they were too complicated and cumbersome. Inspired by a capstan mechanism on the ship, Colt developed a simple revolving ammunition cylinder. Initially, people weren't particularly impressed with the new weapon; but by the 1850s, Colt's company was enjoying phenomenal success. In 1856, he had to churn out 150 guns a day just to keep up with the growing demand! The extremely simple, highly reliable weapon had a profound effect on life in the United States and later in the rest of the world. Armed with a revolver, anybody could kill another person in a matter of seconds. War, crime, law enforcement and even everyday arguments were infused with a new deadly element. In this edition of HowStuffWorks, we'll look at the basic operating principle of the revolver to see why it remains such a popular weapon after more than 150 years on the market. We'll also look at the basic concepts behind firearms and check out a few of the important weapons that preceded the revolver.

Gun Basics and History To understand how a revolver works, it helps to know something about guns in general. Almost every gun is based on the same simple concept: You apply explosive pressure behind a projectile to launch it down a barrel. The earliest and simplest application of this idea is the cannon. A cannon is just a metal tube with a closed end and an open end. The closed end has a small fuse hole. To load the cannon, you pour in gunpowder (a mixture of charcoal, sulfur and potassium nitrate), and then drop in a cannonball. The gunpowder and cannonball sit in the breech, the rear part of the bore (the open space in the cannon). To prepare for a shot, you run a fuse (a length of flammable material) through the hole so it reaches down to the gunpowder. To fire the cannon, you light the fuse. The flame travels along the fuse and finally reaches the gunpowder.

When you ignite gunpowder, it burns rapidly, producing a lot of hot gas in the process. The hot gas applies much greater pressure on the powder side of the cannonball than the air in the atmosphere applies on the other side. This propels the cannonball out of the gun at high speed. The first handheld guns were essentially miniature cannons; you loaded some gunpowder and a steel ball and lit a fuse. Eventually, this technology gave way to trigger-activated weapons, such as the flintlock gun and the percussion cap.

A percussion-cap gun (left) and a flintlock gun (right), two important steps on the way to modern firearms

Flintlock guns ignited gun powder by producing a tiny spark, while percussion caps used mercuric fulminate, an explosive compound you could ignite with a sharp blow. To load a percussion-cap gun, you poured gunpowder into the breech, stuffed a ball in on top of it, and placed a mercuric fulminate cap on top of a small nipple. To fire the gun, you cocked a hammer all the way back and pulled the gun's trigger. The trigger released the hammer, which swung forward onto the explosive cap. The cap ignited, shooting a small flame down a tube to the gunpowder. The gunpowder exploded, launching the ball out of the barrel. (Check out How Flintlock Guns Work for more information on these weapons.) In the 1800s, the percussion-cap gun slowly gave way to the revolver, which only had to be reloaded every five or six shots instead of after each shot. In the next section, we'll see how this system works.

The Revolver The first revolvers used gunpowder, balls and caps like the earlier percussion-cap pistols. The shooter would load each of the six chambers in the cylinder with gunpowder and a projectile, and place separate percussion caps on corresponding nipples. While the loading procedure was tedious, a shooter could have six rounds fully prepared ahead of time.

In the 1870s, these models were replaced by revolvers that used bullet cartridges instead of gunpowder and caps. Cartridges are a combination of a projectile (the bullet), a propellant (gunpowder, for example) and a primer (the explosive cap), all contained in one metal package.

In a modern revolver, cartridges are loaded into six chambers, each of which can be positioned in front of the gun's barrel. A spring-loaded hammer is positioned on the other side of the cylinder, in line with the barrel. The basic idea of the gun is to cock the hammer back, line up a new cartridge in between the hammer and the barrel and then release the hammer

by pulling a trigger. The spring throws the hammer forward so it hits the primer. The primer explodes, igniting the propellant, which drives the bullet down the barrel. The inside of the barrel is lined with spiraling grooves, which spin the bullet to give it stability. A longer barrel improves stability, since it spins the bullet for longer. Extending the barrel also increases the speed of the bullet, since the gas pressure accelerates the bullet for a longer period of time. In early revolvers, a shooter had to pull the hammer back before each shot and then pull the trigger to release the hammer. In modern revolvers, simply pulling the trigger will force the hammer backward and then release it. You can see how a modern revolver works in the diagram below.

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Click on the trigger to fire the gun.

The sequence of events in each shot is very simple: • • •

The trigger lever pushes the hammer backward. As it moves backward, the hammer compresses a metal spring in the gun stock (the handle). The diagram above shows a coiled spring; uncoiled tension springs are also used in revolvers. At the same time, a pawl attached to the trigger pushes on a ratchet to rotate the cylinder. This positions the next breech chamber in front of the gun barrel.

• • •

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Another pawl lodges in a small depression on the cylinder. This stops the cylinder in a particular position so it is perfectly lined up with the barrel. When the trigger lever is pushed all the way back, it releases the hammer. The compressed spring drives the hammer forward. The firing pin on the hammer extends through the body of the gun and hits the primer. The primer explodes, igniting the propellant.

The propellant burns, releasing a large volume of gas. The gas pressure drives the bullet down the barrel. The gas pressure also causes the cartridge case to expand, temporarily sealing the breech. All of the expanding gas pushes forward rather than backward. To reload the gun, the shooter swings the cylinder out and pushes on the ejector rod to operate the extractor in the middle of the cylinder. The extractor grabs the base of the spent shells and removes them from the cylinders.

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To reload, the shooter can place individual cartridges into the chambers or load six at once with a speed loader (basically, a small metal holder with cartridges secured in the right position).

In double-action revolvers, the shooter can either pull the trigger to cock and fire or pull the hammer back ahead of time. The advantage of cocking the hammer first is that the trigger moves more easily when it is time to fire. Obviously, a revolver is easier to use than a flintlock or a percussion-cap weapon. A shooter can load six shots at a time and only needs to pull the trigger to fire. But revolvers seem very limited next to newer technologies: The shooter must pull the trigger for every shot and stop to reload regularly. On the battlefield, the revolver can't possibly stand up to modern automatic weapons. The enduring popularity of revolvers is due to the simplicity of their design. Everything fits together so well that the guns very rarely jam. And since they are made with a relatively small number of parts, they are relatively inexpensive to manufacture. For the home defender and criminals alike, it is an ideal, affordable weapon.

FLINTOFF GUNS:

If you have ever studied American history, you are sure to have heard about the flintlock. The flintlock mechanism was the first reliable and relatively inexpensive system for firing a gun, and was hugely popular in colonial America. It was first developed in the mid-1500s and spread until, by 1660, the English Army adopted the flintlock system for its "Brown Bess" guns. The Brown Bess became famous because of its widespread use during the American Revolution. The flintlock remained popular until the mid-1800s, when it was replaced by the percussion-cap lock. By the time of the civil war, nearly all guns manufactured used the percussion cap. That means that the flintlock, as a technology, lasted about 300 years!

The flintlock gun and the flintlock itself are fascinating devices. There are at least four things that make them so interesting: • • •

Next to the pendulum clock, the flintlock gun was probably the most technologically advanced device that anyone commonly owned at the time. The flintlock is incredibly important historically. Colonial America depended on it for food, protection and warfare. The flintlock itself is amazing from a mechanical standpoint.

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The flintlock is the foundation of all modern guns. If you want to understand how modern guns work, you get the best view by understanding the flintlock. A flintlock gun is the simplest reliable gun possible, and it can teach you a great deal about the technology behind guns in general.

A Little History Guns have been around for an incredibly long time, and they started with the cannon. The World Book encyclopedia discusses the first significant use of a cannon at around 1350 AD, making it one of the oldest pieces of modern technology still in use.

A cannon is a remarkably simple device. It consists of a strong metal tube with a plug at one end. There is a small hole for a fuse drilled through the tube. You load gunpowder into the tube from the open end of the cannon and then insert a cannon ball so that the gunpowder and ball are pressed against the plugged end. You stick a fuse in the small hole and light it to ignite the gunpowder (or you can pour a little gunpowder in the hole and light the gunpowder instead of using an actual piece of fuse). The explosion shoots the cannonball away from the cannon at high speed. The first guns were essentially hand cannons -- small tubes that the user loaded with gunpowder and a ball and lit from the outside. Around 1400, hand cannons were fairly common, and people were even using four-barrel hand cannons! You loaded each little cannon separately and lit each one when you needed it. The hand cannon required two technological improvements to make it into a useful tool: •

First, it needed a shape that worked for the shooter -- the early hand cannons were essentially sticks that the shooter held in his or her hand. • There had to be a good way to light the gunpowder quickly. Wouldn't it be nice if you could fire the gun at the touch of a button (trigger)? It is interesting to think of the early guns as the first button-operated appliances! A lock is the ignition mechanism for a gun, and several locks preceded the flintlock. For example, the matchlock was simply a piece of slow-burning rope that you would light ahead of time and then move into position to light the gunpowder. The slow-burning rope was attached to a lever that you moved with your finger to rotate it into position -- the first trigger. Obviously, the matchlock had several problems: • You had to light the rope ahead of time.

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The rope could burn itself out if you took too long between lighting it and firing the gun. • It glowed, so people could see it at night. • Rainy weather would put it out. Despite these problems, matchlocks were common for 200 years because they were a better option than lighting the gunpowder by hand and they were cheap to build. What the world needed was a way of igniting gunpowder in the barrel of a gun that was instant, reliable and fairly weatherproof. It also needed to be relatively inexpensive and easy to make. The flintlock was the technological marvel that solved all of these problems!

The Flintlock Mechanism The Merriam Webster Dictionary describes a lock, in the context of a gun, as "The method for exploding the charge or cartridge of a firearm." The flintlock is the most venerable of the lock technologies. The flintlock mechanism, like the pendulum clock mechanism, is amazing from an innovation standpoint. This single device solved so many of the problems of the time, and it did so using the fairly primitive tools and technology already available then. The flintlock was quite an accomplishment! The basic goal of the flintlock is simple: to create a spark that can light the gunpowder stored in the barrel of the gun. To create this spark, the flintlock uses the "flint and steel" approach. The idea behind flint and steel is straightforward. Flint is an amazingly hard form of rock. If you strike iron or steel with flint, the flint flakes off tiny particles of iron. The force of the blow and the friction it creates actually ignites the iron, and it burns rapidly to form Fe3O4. The sparks that you see are the hot specks of iron burning! If these sparks come near gunpowder, they will ignite it. The flintlock therefore needs: • • •

A piece of flint A piece of steel A place for the sparks to touch gunpowder The flint needs to move at high speed and strike the steel in such a way that the sparks fall into some gunpowder. You can see the four parts that make this happen in the picture below.

The flintlock

The main parts of a flintlock are: • • • •

The hammer, which holds and accelerates a piece of flint The mainspring, which powers the hammer The frizzen, which is the piece of steel the flint strikes The pan, which is the place where a small quantity of gunpowder waits to receive the sparks You can see these parts labeled in the picture below.

These four pieces are all that the flintlock actually needs to accomplish its goal, but all flintlocks also solve the problems of loading the pan, protecting the pan from the weather and triggering the hammer, so there are three additional parts: •

The tumbler, which holds and releases the power of the mainspring and transmits it to the hammer • The sear and sear spring, which engage the tumbler and release it when someone pulls the trigger • The frizzen spring, which holds the cover attached to the frizzen over the pan to make the flintlock weatherproof The mainspring presses against the tumbler and is able to rotate the hammer with a great deal of force. The sear engages the tumbler when the gun is cocked and holds the force of the mainspring. When you pull the trigger, it pushes the sear enough to release the tumbler and allows the hammer to drive the flint forward. You can see all of these parts in the image below.

The back of the flintlock

When you work with a flintlock and watch a flintlock in action you can see how all of these pieces work together. A flintlock has three positions for the hammer: uncocked, half-cocked and fully cocked. In the fully cocked position, the gun is ready to fire. If the trigger moves the sear just a bit, it releases the tumbler. In the half-cocked position, you can load the gun. The trigger is locked in the half-cocked position and cannot release the tumbler. After you fire the gun, it is in the uncocked position. The following images show you these three positions from both sides of the lock, which allows you to understand how the sear and tumbler work together:

The flintlock in the uncocked position

The flintlock in the uncocked position

Note how the shape of the tumbler locks the half-cocked position:

The flintlock in the half-cocked position

The flintlock in the half-cocked position

The flintlock in the fully cocked position

The flintlock in the fully cocked position

The frizzen at the flint's point of impact

In addition, the frizzen has the ability to move. In the cocked position the frizzen is down, covering the pan. When the flint strikes it, the frizzen pops out of the way to expose the pan. The frizzen spring holds the frizzen in both positions. To use a flintlock, you follow these steps: (see the links at the end of this article for much more detailed instructions): • • •

Half-cock the hammer. Pour a measure of gunpowder down the barrel. Wrap a lead ball (the bullet) in a small piece of cloth or paper and ram it down the barrel on top of the gunpowder. The bullet/cloth combination will have a nice, tight fit. • Place a small amount of gunpowder in the flintlock's pan. • Snap the frizzen in place over the pan. • Fully cock the hammer. • Pull the trigger to fire the gun. When you fire the gun, the flint strikes the frizzen and shaves off iron to create sparks. The hammer's blow also snaps the frizzen back to expose the gunpowder in the pan. The pan's gunpowder ignites, and it flashes through a small hole in the side of the barrel to ignite the gunpowder inside the barrel. The gun fires!

The Barrel The barrel of a flintlock is its own technological marvel, especially for the time. A blacksmith would take a flat piece of iron and beat it into a cylindrical shape around a mandrel -- a long rod of the proper diameter. By heating the iron to a high enough temperature in a forge, the blacksmith actually welded the seam along the length of the barrel to form a strong tube. This process could take days. Barrels ranged anywhere from pistol length (6 to 12 inches, 15 to 30 cm) to long gun length (40 to 60 inches, 102 to 152 cm).

The blacksmith could finish the interior of the barrel as either a smooth bore or a rifled bore. A smooth bore is just that -- smooth along the entire length of the barrel. The Brown Bess of the American Revolutionary War was smooth bored. So is any shotgun. Drilling out the tube with successively larger bits and then polishing with a reamer creates a smooth bore barrel. Rifling a barrel is a way of increasing the accuracy of the bullet, whether the bullet is spherical or cone shaped. To rifle a barrel, you start with a smooth bore and engrave spiral grooves down the inside of the barrel. A typical pattern is one twist of the grooves in 48 inches (122 cm) of barrel length. As the bullet speeds down the barrel it engages the grooves, exiting the barrel with a rapid spin (between 1,000 and 3,000 RPM) and traveling at a speed of 1,000 to 2,000 feet per second (305 to 610 meters per second) through the air.

You can see the spiral grooves cut into this barrel.

Once the barrel is smoothed or rifled, one end is closed off with a breech plug. Then, a small hole is drilled in the barrel to allow the flame from the flintlock's pan to enter the barrel and ignite the charge.

The Complete Gun The expression "lock, stock and barrel" goes way back, and is directly related to the manufacture of guns. To assemble a complete gun you need all three parts: • The lock - the firing mechanism (along with the trigger) • The stock - the wooden parts of the gun that give it its shape and make it easy to hold • The barrel - smooth bore or rifled (complete with breech plug) If you have all three parts, you can assemble a complete gun. In colonial America, a person wanting a gun might have gone to a gunsmith for a complete firearm, or might have purchased the barrel and lock and created the stock him- or herself.

Lock, stock and barrel

A percussion lock (see next page) with the trigger and the trigger guard

The stock is a fairly intricate piece of carving. It has to accept the barrel, the lock, the trigger and the trigger guard. In the following two pictures you can see the necessary woodwork, and you can also see how the trigger and the lock fit together in the stock.

The trigger ready to fit into the stock

The trigger in the stock

When you pull the trigger, the piece of metal within the stock pushes upward against the sear pin and releases the tumbler so the hammer falls. A complete gun also included several decorative brass fittings for the nose and the butt of the gun, as well as a ramrod and a ramrod holder underneath the barrel. The main challenge in assembling the gun, besides the obvious woodworking talent necessary to carve the stock, is getting everything to line up. The barrel has a hole in its side and the pan of the flintlock must align perfectly with it.

The hole in the barrel is tiny. It is hard to see in the picture above, but it is in the middle of a screw-in piece of this modern flintlock reproduction.

The Flintlock's Replacement: Percussion Cap Flintlocks lasted a remarkably long time, but they were eventually replaced by a lock and ignition system called the percussion cap. The percussion cap was easier to load, more weather resistant and more reliable, so by the time of America's civil war, both Union and Confederate armies used percussion-cap guns exclusively. The percussion cap was made possible by the discovery of a chemical compound called mercuric fulminate or fulminate of mercury. Its chemical formula is Hg(ONC)2 -- it is made from mercury, nitric acid and alcohol. Mercuric fulminate is extremely explosive, and it is shock sensitive. A sharp blow, or even too much finger pressure, can cause it to detonate. By putting a small amount of mercuric fulminate in a pre-made cap (a tiny cup about the size of a pencil eraser) and affixing the cap to a nipple and tube leading into the barrel, the cap can ignite the gunpowder in the barrel. The transition from flintlock to percussion cap is very minor, and many flintlocks were converted. The percussion lock is exactly the same as the flintlock in terms of the mainspring, hammer, tumbler, sear and sear spring. The hammer has uncocked, half-cocked and fully cocked positions just like the flintlock. What the percussion lock does not have is the flint and frizzen. Instead, there is a nipple that accepts the cap, and this nipple contains a tube that leads the flame from the cap down to the main charge of gunpowder in the barrel. The hammer is shaped to strike the cap on the

nipple and cover it so the nipple does not get blown off. These pictures help you understand the percussion lock:

The nipple attached to the end of the barrel

A percussion-cap lock in an unfinished stock

The percussion hammer in the cocked position: The cap, about the size of a pencil eraser, fits over the end of the nipple.

The percussion hammer in the uncocked position

The percussion lock did not last very long -- perhaps 50 years. Manufacturing processes were developing rapidly at the time and it became possible to integrate the cap, powder and projectile into a single metal package at low cost. These bullets are what we use today!

How does a gun silencer work? It is amazing that anything is able to silence a gun, but gun silencers actually work on a very simple principle. Imagine a balloon. If you pop a balloon with a pin, it will make a loud noise. But if you were to untie the end of the balloon and let the air out slowly, you could pop it making very little noise. That is the basic idea behind a gun silencer. To fire a bullet from a gun, gunpowder is ignited behind the bullet. The gunpowder creates a high-pressure pulse of hot gas. The pressure of the gas forces the bullet down the barrel of the gun. When the bullet exits the end of the barrel, it is like uncorking a bottle. The pressure behind the bullet is immense, however -- on the order of 3,000 pounds per square inch (psi) -- so the POP that the gun makes as it is uncorked is extremely loud. A silencer screws on to the end of the barrel and has a huge volume compared to the barrel (20 or 30 times greater). With the silencer in place, the pressurized gas behind the bullet has a big space to expand into. So the pressure of the hot gas falls significantly. When the bullet finally exits through the hole in the silencer, the pressure being uncorked is much, much lower -- perhaps 60 psi. Therefore, the sound of the gun firing is much softer

HAND GONNE

The earliest 'hand gonne' was developed in the fifteenth century, but was not a great influence in battle. It was a small cannon with a touch-hole for ignition. It was unsteady, required that the user prop it on a stand, brace it with one hand against his chest and use his other hand to touch a lighted match to the touch-hole, and had an effective range of only about thirty to fourty yards. It surely must have taken iron nerves to use one of these against a charging knight, nearly within his lance's reach, when the powder might not even ignite

FLASH PAN

Users of primitive cannons and 'hand gonnes' came to realize that a more reliable ignition system was needed. It was just too difficult to use one hand to touch a lit match to an open hole in the gun barrel in the heat of battle while trying to hold the gun steady with the other hand. Also, there was often not enough gunpowder exposed at the touch-hole to ignite reliably. So, the gun designers had to come up with a more reliable system to get the gunpowder lit in a hurry. Eventually, a clever invention was devised to solve the problem. The touch hole was moved to the side of the gun barrel, and a cup was placed at the opening with a lid on it. This cup would hold a small amount of gunpowder which could be easily ignited. When the powder began to burn, some of the fire would go through the touch hole and ignite the gunpowder inside the barrel, thereby firing the gun. This cup was called the "Flash Pan". The cover on the flash pan prevented the powder from blowing away in the wind or from getting wet in a fog. The above animation shows a top view of a gun barrel with flash pan. All the later ignition systems on guns with a flash pan were designed to automatically ignite the gunpowder in the flash pan at the press of a lever or trigger. This was accomplished by either putting the end of a burning wick into the flash pan or using a flint and steel combination to throw sparks into the flash pan.

MATCHLOCK

The Matchlock was a welcome improvement in the mid-fifteenth century and remained in use even into the early 1700s, when it was much cheaper to mass produce than the better classes of firearms with more sophisticated ignition systems. The Matchlock secured a lighted wick in a moveable arm which, when the trigger was depressed, was brought down against the flash pan to ignite the powder. This allowed the musketeer to keep both hands on the gun, improving his aim drastically. The gun had its weaknesses, though. It took time to ignite the end of the wick, which left the musketeer useless in case of a surprise attack. Also, it was difficult to keep the wick burning in damp weather. For the most part, longbowmen were more effective in battle than the musketeers. The one real advantage the musketeers possessed was the intimidation factor which their weapons provided. The first important use of musketeers was in 1530 when Francis I organized units of arquebusiers or matchlock musketeers in the French army. By 1540 the matchlock design was improved to include a cover plate over the flash pan

which automatically retracted as the trigger was pressed. The matchlock was the primary firearm used in the conquering of the New World. In time, the Native Americans (Indians) discovered the weaknesses of this form of ignition and learned to take advantage of them. Even Henry Hudson was defeated by an Indian surprise attack in 1609 due to unlit matches. The matchlock was introduced by Portuguese traders to Eastern countries around 1498, particularly India and Japan, and was used by them well into the 19th century.

WHEEL LOCK

The Wheel Lock was the next step in firearms evolution. It is said to have been invented by Johann Kiefuss of Nuremberg in 1517, and the idea probably came from the spring driven tinder lighter in use at the time. The idea of this mechanism is simple. Have you ever used a modern lighter which has a flint pressed up against a roughened metal wheel? When you spin the wheel with your finger, the flint pressed against its surface throws off sparks. The same system was used in these firearms to create sparks as needed to ignite the gunpowder to fire the gun. No more waiting to get a wick lit, and no more stressing about it going out when the fog rolls in. In 1530, Charles V, the Holy Roman Emperor who ruled over Spain and Austria, imported the brothers Marquarte to transfer their workshops from Augsburg to Madrid. They brought to Spain unsurpassed knowledge of firearms production. The wheel lock design was eventually improved with more durable springs, their main weak point, and a cover over the wheel mechanism to protect it and keep it dry. The wheel lock was an expensive gun to make and a matchlock cost less than half as much, so it was impossible to equip a complete army with the more costly mechanism. Only a person of substantial wealth could afford one for himself. By around 1560 German gunsmiths were using wooden stocks and adorning them with inlays of ivory and horn. At about this time the metal parts were fire-blued to add extra beauty and to protect against corrosion. Also, metallurgy had improved to the point that gun barrels were no longer bursting very often. The strongest barrels were of damascene manufacture. In this process, strips of metal about the thickness of a man's finger are wound together. Then, another strip is wound around them for the full length of the piece, then the whole thing is heated and welded. It is hammered and forged into the final shape, then bored out. The damascene barrel was the only one that could survive being packed

for its full length with gunpowder then fired. Other gun barrels were at risk with only a quarter of their length packed.

SNAPHAUNCE

The Snaphaunce first appeared around 1570, and was really an early form of the Flintlock. This mechanism worked by attaching the flint to a spring-loaded arm. When the trigger is pressed, the cover slides off the flash pan, then the arm snaps forward striking the flint against a metal plate over the flash pan and hopefully produces enough sparks to ignite the powder. This mechanism was much simpler and less expensive than the Wheel Lock. The German gunsmiths, who tended to ignore the technical advances of other nationalities, continued to produce and improve upon the wheel lock up until the early 18th century

FLINTLOCK

The Flintlock was developed in France around 1612. A key contributor to this development was Marin le Bourgeoys who was assigned to the Louvre gun shops by King Henri IV of France. The Flintlock's manufacture slowly spread throughout Europe, and by the second half of the century it became more popular than the Wheel Lock and Snaphaunce. The main difference between the Flintlock and Snaphaunce is that in the Flintlock the striking surface and flashpan cover are all one piece, where in the Snaphaunce they are separate mechanisms. This made the mechanism even simpler, less expensive, and more reliable than its predecessor. This simplicity allowed for more creative gun designs, such as guns with multiple barrels and miniature pistols which could be concealed easily inside a garment. By 1664 experiments with rotating-block repeated fire guns were under way (like a revolver which holds a number of shots in a rotating cylinder) but such weapons were dangerous to operate and would have to wait for another century and a half to be made a standard weapon.

The northern Arabs acquired the Snaphaunce and Flintlock in the late 1600s and often designed their long guns with a sharply curving butt so that they could be tucked under an arm and fired single-handed from the back of a camel or horse. In the early 1700s the Brown Bess Flintlock made its appearance. It probably got its name from the acid-brown treatment of its barrel. I mention this so that any flintlock owners with those brown-treated guns (like mine!) will understand just how late in the game they appeared. By this time, the flintlock was accurate up to about 80 yards but nobody could aim at a man and kill him at 200 yards. A shooter of average experience could load and fire two to three rounds per minute.

For more information on Flintlocks and Percussion Cap arms and enthusiasts, visit the Kentucky Long Rifle page at http://www.webpub.com/~jhagee/ky-lr.html.

PERCUSSION CAP

The Percussion Cap ignition system was developed in 1805 by the Reverend John Forsyth of Aberdeenshire. This firing mechanism is a great step in advancement from its predecessors because it does not use an exposed flashpan to begin the ignition process. Instead, it has a simple tube which leads straight into the gun barrel. The key to this system is the explosive cap which is placed on top of the tube. The cap contains fulminate of mercury, a chemical compound which explodes when it is struck. This is the same stuff as is used in the paper or plastic caps in a child's cap gun. As illustrated above, when the cap is struck by the hammer, the flames from the exploding fulminate of mercury go down the tube, into the gun barrel, and ignite the powder inside the barrel to propel the bullet. This firing mechanism provided a major advance in reliability, since the cap was almost certain to explode when struck. This mechanism is almost immune to dampness, though in a rainfall one must still be cautious to avoid getting water in the gun barrel or into the ignition system while loading the weapon. The percussion cap was the key to making reliable rotating-block guns (revolvers) which would fire reliably, and in the early 1800s several manufacturers began producing these multiple-shot sidearms in mass quantities. The percussion cap firing mechanism gave an individual soldier a weapon of precision and reliability which was used to devastating effect in the U.S. Civil War.

GUN POWDER

From The Foxfire Book, Volume 5 - © 1979 The Foxfire Fund; Published by Doubleday Books "Black powder is and isn't hard to make depending on which end you look at it from. It is a long and tiresome task if you make more than ten pounds at a time. "Out on the West Coast, as in some southern states, the trend by the government is to prevent its sale with mountains of red tape. Making your own black powder, however, is not unlawful as yet, as far as I know." "By weight measure, black powder is made of seventy-five parts saltpeter finely ground, fifteen parts charcoal, and ten parts sulfur. All ingredients must be fine ground separately. This can be accomplished with either a mortar and pestle, or with a hand-cranked flour mill. Never mix all three ingredients before grinding unless you want to turn your mill into a deadly grenade, or your mortar into a cannon that can blow off your fingers or even your hand." "Then the ingredients can be mixed with a small amount of water so the mixture comes out with biscuit-dough consistency. Usually when I mix the ingredients, I add just enough stale urine to make the batch bunch about like biscuit dough. The urine, substituted for water, gives the powder more oxygen and higher performance." "Flowers of sulfur is ideal for gun powder, and it can be bought in most drug stores in four-ounce bottles or pound cans." "It can also be found in pure deposits around volcanoes, and in early times, because it was found where molten lava issued from the earth, the sulfur condensed around the rims of the volcanoes was called brimstone." "Today, in certain places around the world, sulfur is recovered from un- derground deposits by pumping live steam underground through pipes. The sulfur melts and, being lighter than water, is easily pumped out at another point close by. Then it is pumped into big ships that haul it to industries all over the world. That's why you can buy a hundredpound sack for about three dollars in most places. "Saltpeter, the chemical that produces the oxygen for the other ingredients when lit off, can he made by putting urine and manure of any kind in a big cement tank mixed with water until you have about three hundred gallons mixed up. Then you put on a tight lid and let it sit for about ten months. You have to have a drain pipe and valve at the bottom,

and a stainless steel filter screen installed beforehand or you'll have one big mess on your hands. At the end of that time, you run the liquid that drains off through ashes into shallow wooden trays lined with plastic sheeting and let them stand for evaporation in the sun. When the water evaporates, potassium nitrate crystals (saltpeter) will form in the bottom of the trays." "In the old days in cities, most outhouses were fitted with trays or drawers under the seats that could be pulled out from behind the building. They had night-soil collectors who were paid so much every month by the outhouse owners to keep those drawers emptied, and they'd come around with a special wagon into which they dumped the contents. When the wagon was full, it was hauled out to where another fellow bought the contents and dumped it into concrete tanks where the bacteria works it just like yeast works wine or bread dough. Then the liquid was run through ashes into shallow tiled or plain concrete evaporating trays or basins to recover the saltpeter." "Today, saltpeter can also he bought in most drug stores in bottles or cans." "Charcoal provides the carbon needed when the powder is lit off. When burning, the carbon assists in making potassium carbonates and carbon sulfates during the one one hundredth of a second that it is burning. Most of this is released at the muzzle of a smoke pole in the form of powder smoke. Some remains in the barrel in the form of fouling and should be swabbed out about every third shot if the shooter wants the round ball to continue to shoot true." "The charcoal should never be made from hardwood as hardwood has too much ash. Such woods as chinaberry, willow, cottonwood, soft pine with no knots, or redwood and Western cedar make the best grade charcoal. A fifty-five-gallon drum with a snap-on lid and a match-stem-sized hole in the lid set over a fire Pit is a good charcoal maker. Take the wood and chip it or cut it into inch chunks and put a bucketful in the drum. Then build a hardwood fire under the drum and when smoke begins to spurt from the vent, light the wood with a match. When the flame goes out, your charcoal is made. Rake the fire out from under the drum, plug the vent with a bit of asbestos fiber or a nail that fits in tight, and let the drum sit overnight to cook. You can then crush and powder the charcoal with a mortar and pestle, or run it through a hand-cranked grain grinder to a flourlike fineness. " "By the way, Just yesterday I took time out and made batch of powder, and this time, when I mixed the ingredients, I added homemade alder charcoal instead of redwood and improved the powder's performance 100 per cent. I recently bought a tight little sheetmetal heater stove for camp cooking and by accident discovered that getting a load of alder going good and then closing it UP tight and dampering it until it went out and turned cold converted the alder into nice pure charcoal. " "When making black powder, never add any other ingredients or explosive powders unless you wish to turn your muzzle loader into a grenade that can kill you or cripple you for life. Keep your black powder stored in steel, airtight cans in a cool, dry place, and out

of the reach of children. My parents failed to do that, and I've carried powder marks on my face for the last thirty years. A ten-year-old may think he knows what he's doing, but ten years don't give him enough prudence to think many things out ahead of time before he lights that match." "The nice thing about shooting black powder is that commercial black costs about two cents a round, and homemade about a half-cent a round. " As the demand for powder grew in the Southern Appalachians, fairly large operations came into being for its manufacture. As Jim Moran told us, "Powder was made in this area. The big powder mill that was around here is gone now--the place burned up and all. But it was on Boozy Creek, and it was operated back in the early 1800s and possibly before by the Hughes family. They were also gunsmiths. They were somehow connected with the blockhouse which was on the Wilderness Road. That was where Boone wintered after his son was bushwhacked on the Wilderness Road. Now that was quite a settlement around there. One winter I went up on Timbertree Branch near the blockhouse site and there were about ten or fifteen cabins around there made out of poplar logs. They were only about twelve feet square--didn't have any windows or anything in them. I think they were the residue of that holdup of immigration when those people got that far and they were afraid to go on. I went back over there about five years ago, but there's none of that left there now." "But these Hughes, they ground that powder on millstones. I found that out. I know one man who found the old order book for the powder mill. He had it photostated. That mill blew up twice. One time they found shoe tacks in the charcoal. The story was that it was sabotaged. One time it blew a fellow's hand off." "Willow charcoal is what they used for the powder. And then saltpeter- you know you hear about saltpeter caves. Over around Saltville they've found a lot of the vats and stuff where they leached that out from bat guano. That was done during the Civil War. In fact, they've uncovered one of those caves in the last ten years or so and found the vats still intact in the cave. That's Saltville, which is about thirty-five or forty miles north of here. And the same thing in Big Stone Gap. Powder for the Battle of King's Mountain was made on Powder Branch near Erwin, Tennessee." Another of these operations was located in Mammoth Cave. Recently, in a remarkable experiment there, potassium nitrate crystals from saltpeter were produced again in the traditional method. Carol A. Hill, one of the coordinators for the Saltpeter Research Group, describes the procedure that was used that day:

"Before the 187Os, caves were the primary source of nitrate used in the manufacture of gunpowder. Saltpeter mining was one of the first major industries of the new frontier, and one of the principle objectives of exploring new territory was to find saltpeter caves. Caves were mined by individuals and also commercially for national defense purposes during the Revolutionary War, the War of 1812, and the Civil War. Many homesteaders in the Virginias, Kentucky, and Tennessee had their own individual saltpeter caves and from them would make their own gunpowder in home-constructed V-vats or 'hoppers.' "Making a V-vat entailed using a peg-and-hole construction. The holes were made with a hand auger; the pegs by whittling down the end of a log with a hatchet and then by trimming with a knife . The frame was then pounded together with a wooden mallet . A froe was used to make the side boards. Bolts of wood that were straight-grained and well seasoned were the best for this purpose. The glut was used as a wedge to split the log base of the collecting trough. The trough was then hewn out with a foot adze and hatchet. After the hopper was constructed, twigs were laid in the bottom of the vat, and then wheat straw was laid on top of the twigs and along the side boards to help keep the vat from leaking. "Cave dirt was tested for its nitrate potential by the following procedure: A footprint or mark was made in the dirt and left for twenty-four hours. If the print was scarcely visible by the next day, then the dirt was deemed high in niter. A mattock was used to break up the cave dirt, and a wooden saltpeter paddle was used for digging and scraping The dirt was removed from the cave in gunny sacks and poured on top of the twig and straw in the V-vat. Buckets of water were then poured over the saltpeter dirt to leach it of its nitrate or 'Mother liquor'. The mother liquor (also sometimes called 'beer' would run down the sides of the V-vat and into the split-log base and out into the collecting trough. A dipper gourd was often used to transfer the mother liquor into a container. This same liquor was poured again and again over the saltpeter dirt because releaching caused more nitrates to be dissolved. According to the old reports, releaching went on until the solution was of sufficient density to float an egg. "The next step was to combine the mother liquor rich in calcium nitrate with wood ashes that contain high amounts of potassium hydroxide. The best woodashes for this purpose were made by burning hardwoods such as oak and hickory. The mother liquor was either poured directly over the woodashes or the woodashes were leached in barrels and the leachate directly combined with the mother liquor. Upon combination, a white haze could be seen , and this white precipitate (calcium hydroxide or 'curds' as it was called) would slowly sink to the bottom of the barrel. If the solution contained an excess of calcium nitrate, the product was termed 'in the grease.' An excess of woodashes produced a condition called 'in the ley.' The wood ash leachate was poured into the mother liquor until the white curds could no longer be seen precipitating out of solution. The remaining solution thus contained the

still soluble potassium nitrate. This solution was dipped out into an apple-butter kettle (or"evaporator'), and a fire started under the kettle. Turnip halves were then thrown into the boiling solution to help keep it from foaming and to take up the dirty brown color. Oxblood (or alum) was also added to the boiling liquid and caused the organic matter to rise to the top of the liquid and form a scum which, with continued boiling, was constantly ladled off. After a few hours of boiling, the hot liquor was poured through cheesecloth in order to filter out the remaining scum and organic material. Upon cooling, fine, bitter, needle-shaped crystals of niter (potassium nitrate) formed in the liquor. These crystals were then collected and dried. Potassium nitrate crystals were far superior to calcium or sodium-nitrate crystals because they are non-deliquescent (do not take up moisture from the air) and, hence, would not make the gunpowder wet and unusable. The nitrate crystals thus obtained had to be further refined and purified. This purification procedure was done either by the individual and homemade into gunpowder, or it was done after the saltpeter crystals were sent to a refinery where the final gunpowder was made."

SHOT GUN: Shotguns first came into use in the early 1600s. The first two-barrel shotgun appeared in 1873, and the first modern, hammerless, pump-action shotgun was produced in 1904. By the turn of the century, they were immensely popular. Many military officers loved their personal shotguns so much that they brought them along instead of sidearms to World War I, earning them the nickname "trench guns." Since then, they have become a permanent part of the military arsenal and a part of the everyday lives of many civilians as well.

Photo courtesy Shotgun World

Winchester 12-gauge Super X2

Why a shotgun instead of, say, a rifle? Well, to do its job, a projectile must: • •

make contact with the target hit the target in a critical spot With a wider stream of potentially deadly projectiles, a shotgun is like using a can of spray paint if a rifle is like using a felt-tip pen. As long as the target is within its effective range, a shotgun will give you a much better chance of making critical contact with one pull of the trigger. The shotgun is the Swiss-army knife of guns. It is an indispensable tool -- on the farm, in combat and on the hunt. They are just as useful in non-lethal situations, like for scaring away pests or for opening locked doors in a police or military situation, as they are for big game hunting. In this article, you'll find out how shotguns work, what different types are out there and about the various types of ammo a shotgun can accommodate.

The Basics Whether you're talking about a handgun, a rifle or a shotgun, all modern guns have to do some of the same things. They have to send ammunition flying out of a long cylinder called a barrel, and they have to allow for the loading and unloading of new and spent ammunition. When you pull the trigger, a hammer or firing pin strikes an explosive charge on the back of a cartridge or bullet. This causes a small explosion that changes the air pressure in the barrel, forcing whatever was in front of the explosion (such as a bullet or metal pellets) out the other side at an extremely fast speed.

The Basics Whether you're talking about a handgun, a rifle or a shotgun, all modern guns have to do some of the same things. They have to send ammunition flying out of a long cylinder called a barrel, and they have to allow for the loading and unloading of new and spent ammunition. When you pull the trigger, a hammer or firing pin strikes an explosive charge on the back of a cartridge or bullet. This causes a small explosion that changes the air pressure in the barrel, forcing whatever was in front of the explosion (such as a bullet or metal pellets) out the other side at an extremely fast speed.

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Target practice

Shotguns are designed to fire batches of small projectiles instead of single bullets with each pull of the trigger. These projectiles themselves don't have to be aerodynamic like bullets and aren't expected to travel long distances. They are designed to cause their worst damage at closer ranges. Shotgun ammo comes in varying shapes and sizes and includes lead, steel and bismuth pellets, bean bags, rock salt and rocket-like sabots. Shotguns can also fire individual metal slugs.

Know Your Shotgun Parts All shotguns have some of the same basic components. Starting from the end nearest to the shooter, there's often a stock that allows you to steady it against your shoulder muscles. Some manufacturers put a recoil pad at the end of the stock to help dampen the kick you feel when you fire it. There are some shotguns, usually "assault" style, that have foldaway stocks or no stock at all. Moving forward from the stock, you'll find all of the parts associated with firing. This includes the trigger that connects to the sear and hammer. Some shotguns have a pistol grip that extends downward below the trigger.

The hammer activates the bolt assembly and firing pin, which rests against the cartridge to be fired. Now we're at the chamber, where the loading, unloading and firing happens. The chamber can be accessible from the side or the top. Connecting to the chamber is the barrel, which is the long tube that the ammo travels through as it leaves the gun. Some shotguns have a magazine connected to the chamber -- this may take the form of a second, shorter tube below the barrel or else a drum or rectangular cartridge that snaps into the barrel. There may also be a fore-end (a sliding handle colloquially known as a pump) attached to the shorter tube, which is used to partially automate the loading and unloading process. On the top of the barrel, you'll often find a bump that's used as a crude sight.

Making a Barrel Creating a long, straight, consistent hollow tube that can stand up to over 5,000 psi of pressure is one of the hardest parts of making a shotgun or rifle. First, a gunmaker takes a superstrong chrome molybdenum or stainless steel bar and uses a specialized gun drill to hollow it out. Unlike normal drills, most gun drills spin the steel bar instead of the drill bit. As the bit moves along inside the tube that guides its path, the machine shoots oil down the tube to clear the debris, lubricate the path and keep it cool. It takes about a half hour to drill out one barrel. This gets most of the work done, but the resulting hole is usually not large or consistent enough yet. A second machine reams out the last few thousandths of an inch and makes the diameter consistent along the whole barrel.

Measuring Up: Gauge vs. Caliber Shotgun sizes have always been measured in a somewhat roundabout way. You would think that the "12" in a 12-gauge shotgun corresponds to some linear measurement -- maybe inches or centimeters. But that's not the case. "12-gauge" means you can make 12 lead balls, each of equal diameter to the gun barrel, out of 1 pound of lead. This originated in the

days when you would buy lead by the pound to make your own ammo. The gauge told you how many rounds you could make for the gun from 1 pound of lead.

The smaller the gauge number, the wider the barrel. The largest shotgun is a 4-gauge. The .410 shotgun, the smallest, is an exception to the rule: It's actually a .410-caliber -- it has a .41-inch barrel diameter. In general, the smaller the barrel diameter, the less "kick" or recoil the shooter feels from the gun. Many experts say that a 20-gauge shotgun is a good beginner's gun because it has relatively little recoil but fires more shot per shell than the smaller-diameter .410-caliber.

Action and Barrel Types Besides firing, another thing shotguns have to do is set a new cartridge in the chamber and get rid of what's left over from a cartridge that has just been fired. Over time, shotgun manufacturers have developed several different technologies to accomplish this. As new innovations have come along, most of the old designs have stuck around, though. Some of the simplest ways to accomplish the task are still the most effective and dependable.

Photo courtesy Integrated Logistics Support Center (ILCS)

12-gauge Winchester model 1200

One way individual shotguns differ in loading and unloading is in their anatomy. The vast majority of shotguns are either single-barrel, double-barrel side-by-side or double-barrel over-under. The action, or method a shotgun uses for loading and disposing of cartridges, can be: • • • •

autoloading pump action break action bolt action

In the following sections, we'll examine each of these action types

Break, Bolt and Pump Actions

Break Action Break-action shotguns are the most straightforward and the safest, and they're commonly used in shooting competitions. The gun has a hinged opening where the chamber meets the barrel. By opening the gun, it is easy to see if it's loaded or not.

Photo courtesy Shotgun World

SKB Model 485 break-action shotgun

To load a new cartridge, the shooter breaks open the barrel on its hinge, physically places a cartridge into the chamber and then closes it. In older model shotguns, the shooter would have to manually cock the hammer and pull the trigger. In most modern shotguns, there's no need to cock the hammer before pulling the trigger. In most cases after firing the gun, the shooter then manually removes spent cartridges from the chamber and repeats the process to fire again. There are both single-barrel and double-barrel shotguns that are break-action. On modern double-barrel shotguns, there's only one trigger and an automatic or manual barrel selector (the selector picks which barrel fires).

Bolt Action Bolt-action shotguns are not all that common, but they work just like bolt-action rifles. The bolt is a rod attached to a spring, and there's a handle sticking out of it. To load a bolt-action, the shooter twists the bolt handle up and then pulls it back. This both exposes the chamber and cocks the firing mechanism. The shooter then loads a magazine into the chamber and pulls the bolt forward into place. This strips the top cartridge from the magazine, blocks it off from the magazine and prepares it for firing. After firing the first shot, each time the shooter pulls the action back and then forward it ejects the spent cartridge, strips the next cartridge from the magazine and prepares it for firing.

Pump Action Pump-action shotguns also have a moving bolt; but instead of a handle, their bolt system is operated by a wooden or composite slide called the fore-end. In this case, the magazine is a shorter tube under the barrel. First, the shooter fills the magazine with three or more cartridges. There's tension in the magazine from a spring, It's a bit like putting D-cell batteries into an old flashlight. He or she then pulls the fore-end to the rear of the gun. This ejects anything that's in the chamber, cocks the hammer, and loads a shell in the chamber. Next, the shooter pushes the slide forward, which pushes the block and firing pin into the firing position against the cartridge. After each fired shot, the shooter repeats this motion to reload the gun and eject used cartridges.

Autoloading Autoloaders and semi-automatic shotguns take the pump-action idea one step further, using similar mechanisms to those employed by machine guns. As the designs get more complex and have more moving parts, the chances for operator error, misfire and jamming increase dramatically. Autoloaders are considered less reliable than pump-action and break-action guns. The animation below, taken from How Machine Guns Work, shows how a recoil-powered loading system operates.

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Click and hold the trigger to see how a recoil-action gun fires. Please note that the gun in the illustration is a fully-automatic machine gun, and appears only as a reference for its loading system. For simplicity's sake, this animation doesn't show the cartridge-loading, extraction and ejection mechanisms.

Recoil-operated autoloaders use the force naturally generated by recoil from the firing process to eject the spent cartridge, get a new one from the magazine and ready it in the chamber. In this case, the explosion from the cartridge forces both the barrel and the bolt to travel a couple of inches backwards. This ejects the spent cartridge. The barrel and bolt hit springs that send them forward again, and the bolt strips a new cartridge into place on the way. The barrel and bolt lock back into place and are ready to fire again. There are also short-recoil systems that work similarly but with a greater separation between the movement of the barrel and the movement of the bolt.

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Click and hold the trigger to see how a blowback-action gun fires. Please note that the gun in the illustration is a fully-automatic machine gun, and appears only as a reference for its loading system. For simplicity's sake, this animation doesn't show the cartridge-loading, extraction and ejection mechanisms.

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An experienced shooter can repeat the motion of firing and then pumping to reload very quickly. And because the action is all mechanical and linear, it's very simple and unlikely to fail in action.

Automatic Shotguns There are automatic shotguns in limited use in the military, including the USAS-12 and the Franchi SPAS-15. These are rapid-fire, high-impact weapons, allowing the shooter to fire up to four shots per second with one pull of the trigger. The USAS-12 uses a drum magazine, and the SPAS-15 uses a box magazine.

Even more powerful is the Pancor Jackhammer, currently just a concept and prototype weapon. It's an automatic, drum-loaded shotgun made out of plastic. The Jackhammer is extremely light and has a remarkably small recoil. Most of the recoil energy is captured and used in loading and firing the next round. As an interesting additional feature, it is possible to take the drum magazine off the gun, attach a detonator and use it as an anti-personnel mine that fires all of the cartridges at once when tripped.

What's the Difference Between a Shotgun and a Rifle? Handguns and rifles have rifled barrels, meaning that there are grooves cut lengthwise into the inside of the barrel. The grooves cause a bullet to spin, which makes it shoot out straighter and travel faster.

Most shotguns are not rifled inside. With standard ammo like lead or steel shot, a rifled barrel would cause the pieces of shot to bunch up into a tighter pattern, which would defeat the purpose of using a shotgun. For shooters who to more tightly control the spread and impact point of their shot, there are chokes. These are tubes that use a cone or bumpy shape to taper the angle at which ammo leaves the barrel and the distance it travels. Some of them are rifled, and some are not. Some are even adjustable on the fly, meaning you can change the effect without removing the choke.

Choke manufacturers express their expected effects by listing the amount that a choke constricts the barrel and the percentage of shot that will hit a target area at 40 (or, in some cases, 25) yards. In general, the more the barrel is constricted, the higher the percentage of shot hitting the target at 40 yards. But this is all relative to the size and type of shot. Because of this and all of the variables involved (weather, wind conditions, individual barrel, etc.), it's not easy to say precisely how a particular choke will affect the shot pattern, and most shooters have to learn by trial and error.

Extreme Choking: The Sawed-off or Sawn-off Depending on which side of the pond you hail from, you might have heard of "sawed-off" or "sawn-off" shotguns. These are guns whose barrels have been physically shortened with a hacksaw or similar tool to less than 18 inches (46 cm). There are generally two reasons why people make sawed-off shotguns: concealment and spread.

Since they are much shorter, they are easy to hide in a long jacket or down the side of a very long boot. Shortening the barrel also reduces the recoil of a shotgun, which makes it a little easier to use as a one-handed weapon. Since the ammo travels a much shorter distance before dispersing, the shot pattern of a sawed-off is much more spread out. This gives the shooter a much better chance of hitting the target, even if his aim is way off. Sawed-offs are not illegal to own if licensed properly. They require a special registration.

Types of Ammo: Shot Cartridges filled with shot are the most common type of shotgun ammo. Shot are little balls made of any number of metals, including lead, steel, bismuth, tin and zinc.

Each metal behaves a little differently. Lead has some properties that make it one of the most effective materials for shooting game and targets. It is relatively heavy and therefore maintains its explosive force well. It is also somewhat soft, so it changes its shape as it leaves the barrel. This gives it a more spread-out shot pattern than other materials but still delivers a great deal of energy. There is some evidence that because steel pellets do not deform -- they maintain their round shape throughout their flight -- they wound animals without killing them more often than lead. Until the early 1990s, most shot was made of lead. As environmentalists studied its effect on the ecosphere, they found that the spent lead shot hunters left in waterways and forests had harmful effects on wildlife and risked contamination of drinking water. Lead shot has been banned from waterfowl hunting in the United States since 1992, and various types of steel and alloy shot have taken its place. The rule of thumb for shot size is the higher the number, the smaller the diameter of the shot. There is a consistent standard in the United States, but worldwide the numbers don't correspond to any specific measurement across the board. At Chuck Hawks' Shot Pellet Information and Recommendations, you'll find a guide to the various sizes in the United States and what they are used for. In hunting, smaller ammo is used for smaller game, and larger ammo is used for larger game. Buckshot is large-sized shot that got its name because it is used to hunt deer. Because different materials have different weights and characteristics, shot size alone does not tell the whole story. For example, if you are shooting with steel, you'd have to use larger shot than you would if you were doing the same type of hunting with lead.

Types of Ammo: Slugs

Slugs are molded chunks of metal, nylon or plastic. In effect, they turn a shotgun into a crude rifle. Slugs are fired individually, like bullets, instead of in bunches like buckshot and birdshot. They can come in a variety of shapes, but they are often tapered into a bullet shape. They can be solid or filled with substances like explosives or incendiary powder. Shotgun slugs can be rifled -- this is supposed to make them spin in the air and thus improve their flight length and accuracy. One reason hunters use slugs is to hunt deer in states that ban the use of rifles and/or buckshot ammo. The shotgun/slug combination provides a legal, if shorter range alternative. There are at least 20 states that have restrictions of this kind.

Photo courtesy DVI

Mossberg M590/590A1 combat shotgun (center)

Non-explosive slugs are also used for crowd control. When deployed properly, they can act as a non-lethal deterrent in these situations. They are used in organized shooting competitions as well.

Types of Ammo: Sabots A sabot is a specially shaped, two-stage cartridge. It has an outer jacket that helps it travel longer distances, and it has an inner slug or payload. The jacket is designed to fall away in flight after it reaches a certain distance. Several hunting sources suggest that sabot ammunition is only effective at longer distances when shot through a rifled barrel. For a shotgun hunter, this usually means adding on a rifled choke tube.

Sabot can also describe an arrow-like shape of material that fits in a standard shell. One particularly frightening sabot-style payload is the flechette. A flechette round contains hundreds of small, needle- or razor-like projectiles designed to penetrate armor and inflict painful wounds. They are banned by the Geneva Convention but do still see use in combat and counter-terrorism from time to time.

Miscellaneous Ammo •

Breaching rounds - Shotguns are commonly used in the military to "unlock" doors when troops don't know what lies on the other side. Because traditional ammo tends to ricochet and may end up hitting the shooter or someone inside the room, breakable "breaching rounds" are often used. These shells contain a metallic powder that disperses on contact.

• • •

Bean bags - Bean bags are used as shotgun ammo in crowd control situations, as in most cases they stun the victim but do not inflict lasting damage. CS gas grenades - Combat shotguns can be used to disperse tear gas and similar chemicals. Rock salt - Rock salt is a popular home defense ammunition because it reportedly causes severe pain but usually no permanent damage. See DesMoinesRegister.com: Suspect shot with rock salt is caught to read about a case where rock-salt-filled shells were used to disable a burglar.

People will put just about anything in a shotgun and call it ammo. To get an idea of some of the wacky ammunition produced commercially

Shotgun Laws Although there are laws in the United States about purchasing, selling, using and carrying shotguns, these are actually less regulated than most types of guns. Gun-related activity is regulated by the Federal Bureau of Alcohol, Tobacco, and Firearms (BATF). Here are some of the federal laws that apply to shotguns: • Buying restrictions: Certain classes of people are not allowed to purchase shotguns. This includes felons, fugitives, minors under 18, the mentally ill, dishonorable discharges from the armed forces, those under a court order and perpetrators of domestic violence. • Selling restrictions: Sellers must have a federal firearms license or sell through a dealer with a license. They must be licensed by several federal agencies, including the BATF and the Department of Justice. Shotgun sales must be documented with federal form 4473, which maintains the purchaser's information and the gun's serial number. These laws do not apply to antique firearms. • Short-barreled shotguns: The National Firearms Act (NFA) of 1934 makes it illegal to own shotguns with barrels less than 18 inches in length unless they are specifically registered as such with the federal government.

States also have their own firearms laws, which can include waiting periods before purchase, separate registration requirements and bans. See NRA-ILA: Compendium of State Firearms Laws for a general reference to the gun laws in each U.S. state. MACHINE GUNS

Historians count the machine gun among the most important technologies of the past 100 years. As much as any other factor, it set the brutal, unrelenting tone of World War I and World War II, as well as most of the wars since that time. With this machine, one soldier could fire hundreds of bullets every minute, mowing down an entire platoon in only a few passes. Military forces had to develop heavy battle equipment, such as tanks, just to withstand this sort of barrage. This single weapon had a profound effect on the way we wage war.

Photo courtesy Department of Defense

U.S. Marines fire a M-240G machine gun during training exercises at Camp Lejeune Marine Corps Base in North Carolina. Medium machine guns such as this one are an essential element in the modern arsenal.

In light of their monumental role in history, it's somewhat surprising how simple machine guns really are. These weapons are remarkable feats of precision engineering, but they work on some very basic concepts. In this article, we'll look at the standard mechanisms machine guns use to spit out bullets at such a furious rate. Your Browser Does Not Support iFrames

Ballistic Background: Barrel To understand how machine guns work, it helps to know something about firearms in general. Almost any gun is based on one simple concept: You apply explosive pressure behind a projectile to launch it down a barrel. The earliest, and simplest, application of this idea is the cannon. A cannon is just a metal tube with a closed end and an open end. The closed end has a small fuse hole. To load the cannon, you pour in gunpowder (a mixture of charcoal, sulfur and potassium nitrate), and then drop in a cannonball. The gunpowder and cannonball sit in the breech, the rear part of bore, which is the open space in the cannon. To prepare the gun for a shot, you run a fuse (a length of flammable material) through the hole, so it reaches

down to the gunpowder. To fire the cannon, you light the fuse. The flame travels along the fuse, and finally reaches the gunpowder.

When you ignite gunpowder, it burns rapidly, producing a lot of hot gas in the process. The hot gas applies much greater pressure on the powder side of the cannonball than the air in the atmosphere applies on the other side. This propels the cannonball out of the gun at high speed. The first handheld guns were essentially miniature cannons; you loaded some gunpowder, a steel ball and lit a fuse. Eventually, this technology gave way to trigger-activated weapons, such as the flintlock gun and the percussion cap.

A percussion cap gun (left) and a flintlock gun (right), two important steps on the way to modern firearms. To learn more about these weapons, check out How Flintlock Guns Work.

Flintlock guns ignited gun powder by producing a tiny spark, while percussion caps used mercuric fulminate, an explosive compound you could ignite with a sharp blow. To load a percussion cap gun, you poured gunpowder into the breech, stuffed the projectile in on top of it, and placed a mercuric fulminate cap on top of a small nipple. To fire the gun, you cocked a hammer all the way back, and pulled the gun's trigger. The trigger released the hammer, which swung forward onto the explosive cap. The cap ignited, shooting a small flame down a tube to the gunpowder. The gunpowder exploded, launching the projectile out of the barrel. (Check out How Flintlock Guns Work for more information on these weapons.)

Ballistic Background: Cartridge The next major innovation in the history of firearms was the bullet cartridge. Simply put,

cartridges are a combination of a projectile (the bullet), a propellant (gunpowder, for example) and a primer (the explosive cap), all contained in one metal package.

Needless to say, cartridges were a phenomenal success. In fact, they form the basis for most modern firearms. In the next section, we'll see how these sorts of weapons work. The backward motion of the bolt also activates the ejection system. The ejector's job is to remove the spent shell from the extractor and drive it out of an ejection port. Will discuss this in more detail later. But first, let's look at how all of this works -- in a revolver.

Revolvers In the last section, we saw that a cartridge consists of a primer, a propellant and a projectile, all in one metal package. This simple device is the foundation of most modern firearms. To see how this works, let's look at a standard double-action revolver.

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Click on the trigger to see how a revolver fires.

This gun has a revolving cylinder, with six breeches for six cartridges. When you pull the trigger on a revolver, several things happen: •

Initially, the trigger lever pushes the hammer backward. • As it moves backward, the hammer compresses a metal spring in the gun stock (the handle). • At the same time, the trigger rotates the cylinder so the next breech chamber is positioned in front of the gun barrel. • When you pull the trigger all the way back, the lever releases the hammer. • The compressed spring drives the hammer forward. • The hammer slams into the primer at the back of the cartridge, igniting the primer. • The primer sets off the propellent. • The exploding propellent drives the bullet out of the gun at high speed. The inside of the barrel has a spiral groove cut into it, which serves to spin the bullet as it exits the gun. This gives the bullet better stability as it flies through the air, increasing accuracy. When the propellant explodes, the cartridge case expands. The case temporarily seals the breech, so all the expanding gas pushes forward rather than backward.

Revolvers, which come in a range of shapes and sizes, are one of the most popular gun designs of all time. Their design is so simple that they almost never jam or misfire.

Obviously, this sort of gun is easier to use than a flintlock or a percussion cap weapon. You can load six shots at a time, and you only have to pull the trigger to fire. But you're still fairly limited: You have to pull the trigger for every shot, and you need to reload after six shots. You also have to eject the empty shells from the cylinders manually. Now let's take a look at how gun manufacturers addressed the problems inherent in revolvers.

Machine Guns: Guns and Gun Systems

Gatling Gun In the 1800s, gun manufacturers worked up a number of mechanisms to address the problems of limited firing ability. A lot of these early machine guns combined several barrels and firing hammers into a single unit. Among the most popular designs was the Gatling gun, named after its inventor Richard Jordan Gatling. You can see how this weapon works in the diagram below.

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This weapon, the first machine gun to gain widespread popularity, consists of six to 10 gun barrels positioned in a cylinder. Each barrel has its own breech and firing pin system. To operate the gun, you turn a crank, which revolves the barrels inside the cylinder. Each barrel passes under an ammunition hopper, or carrousel magazine, as it reaches the top of the cylinder. A new cartridge falls into the breech, and the barrel is loaded. Each firing pin has a small cam head that catches hold of a slanted groove in the gun body. As each barrel revolves around the cylinder, the groove pulls the pin backward, pushing in on a tight spring. Just after a new cartridge is loaded into the breech, the firing-pin cam slides out of the groove, and the spring propels it forward. The pin hits the cartridge, firing the bullet down the barrel. When each barrel revolves around to the bottom of the cylinder, the spent cartridge shell falls out of an ejection port.

Fully Automatic The Gatling gun is often considered a machine gun because it shoots a large number of bullets in a short amount of time. But unlike modern machine guns, it is not fully automatic. You have to keep cranking if you want to keep shooting. The first fully automatic machine gun is credited to an American named Hiram Maxim. Maxim's remarkable gun could shoot more than 500 rounds per minute, giving it the firepower of about 100 rifles.

Hiram Maxim and one of his early machine gun designs: When Maxim introduced his weapon to the British army in 1885, he changed the battlefield forever.

The basic idea behind Maxim's gun, as well as the hundreds of machine gun designs that followed, was to use the power of the cartridge explosion to reload and re-cock the gun after each shot. There are three basic mechanisms for harnessing this power: • • •

Recoil systems Blowback systems Gas mechanisms

In the next couple of sections, we'll discuss each of these systems.

Machine Guns: Recoil Systems The first automatic machine guns had a recoil-based system. In nature, every action has an equal and opposite reaction. This principle is responsible for the recoil effect in guns. When you propel a bullet down the barrel, the forward force of the bullet has an opposite force that pushes the gun backward. In a gun built like a revolver, this recoil force just pushes the gun back at the shooter. But in a recoil-based machine gun, moving mechanisms inside the gun absorb some of this recoil force. You can see how this works in the diagram below.

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Click and hold the trigger to see how a recoil-action gun fires. For simplicity's sake, this animation doesn't show the cartridge loading, extraction and ejection mechanisms. See the "Machine Gun Feeding: Belt System" section to find out how these components work.

Here's the process: To prepare this gun to fire, you pull the breech bolt (1) back, so it pushes in the rear spring (2). The trigger sear (3) catches onto the bolt and holds it in place. The feed system runs an ammunition belt through the gun, loading a cartridge into the breech (more on this later). When you pull the trigger, it releases the bolt, and the spring drives the bolt forward. The bolt pushes the cartridge from the breech into the chamber. The impact of the bolt firing pin on the cartridge ignites the primer, which explodes the propellant, which drives the bullet down the barrel. The barrel and the bolt have a locking mechanism that fastens them together on impact. In this gun, both the bolt and the barrel can move freely in the gun housing. The force of the moving bullet applies an opposite force on the barrel, pushing it and the bolt backward. As the bolt and barrel slide backward, they move past a metal piece that unlocks them. When the pieces separate, the barrel spring (4) pushes the barrel forward, while the bolt keeps moving backward. The bolt is connected to an extractor, which removes the spent shell from the barrel. There are a number of extractor systems in modern guns, but the basic idea in all of them is fairly simple. In a typical system, the extractor has a small lip that grips onto a narrow rim at the base of the shell. As the bolt recoils, the extractor slides with it, pulling the empty shell backward. The backward motion of the bolt also activates the ejection system. The ejector's job is to remove the spent shell from the extractor and drive it out of an ejection port (more on this later).

When the spent shell is extracted, the feeding system can load a new cartridge into the breech. If you keep the trigger depressed, the rear spring will drive the bolt against the new cartridge, starting the whole cycle over again. If you release the trigger, the sear will catch hold of the bolt and keep it from swinging forward.

Photo courtesy Department of Defense

A U.S. airman fires a GAU-17 mini-gun from a UH-1 Huey during training exercises in Australia. Mini-guns are modern updates of the Gatling gun, with an electric motor, rather than a hand-crank, to rotate the barrels.

The Gatling gun played an important role in several 19th century battles, but it wasn't until the early 20th century that the machine gun really established itself. In the next section, we'll look at the next major step in machine gun evolution.

Machine Guns: Blowback System A blowback system is something like a recoil system, except the barrel is fixed in the gun housing and the barrel and bolt do not lock together. You can see how this mechanism works in the diagram below.

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Click and hold the trigger to see how a blowback-action gun fires. For simplicity's sake, this animation doesn't show the cartridge loading, extraction and ejection mechanisms. See the "Machine Gun Feeding: Belt System" section to find out how these components work.

This gun has a sliding bolt (3) held in place by a spring, a spring-driven cartridge magazine (5), and a trigger mechanism (1). When you slide the bolt back, the trigger sear (2) holds it in place. When you pull the trigger, the sear releases the bolt, and the spring drives it forward. After the bolt chambers the cartridge, the firing pin sets off the primer, which ignites the propellant. The explosive gas from the cartridge drives the bullet down the barrel. At the same time, the gas pressure pushes in the opposite direction, forcing the bolt backward. As in the recoil system, an extractor pulls the shell out of the barrel, and the ejector forces it out of the gun. A new cartridge lines up in front of the bolt just before the spring pushes the bolt forward, starting the process all over again. This continues as long as you hold the trigger down and there is ammunition feeding into the system.

Photo courtesy NARA

A U.S. Marine, fighting in Okinawa, Japan, during World War II, fires a military-issue Thompson's submachine gun. The Thompson's, commonly known as the "Tommy gun," was a popular weapon with both soldiers and gangsters in the 1930s and '40s.

Machine Guns: Gas System The gas system is similar to the blowback system, but it has some additional pieces. The main addition is a narrow piston, attached to the bolt, that slides back and forth in a cylinder positioned above the gun barrel. You can see how this system works in the diagram below.

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Click and hold the trigger to see how a gas-action gun fires. For simplicity's sake, this animation doesn't show the cartridge loading, extraction and ejection mechanisms. See the "Machine Gun Feeding: Belt System" section to find out how these components work.

This gun is basically the same as a blowback-system gun, but the rear force of the explosion doesn't propel the bolt backward. Instead, the forward gas pressure pushes the bolt back. When the bolt swings forward to fire a cartridge, it locks onto the barrel. Once the bullet makes its way down the barrel, the expanding gasses can bleed off into the cylinder above the barrel. This gas pressure pushes the piston backward, moving it along the bottom of the bolt. The sliding piston first unlocks the bolt from the barrel, and then pushes the bolt back so a new cartridge can enter the breech. The diagrams we've presented only depict particular examples of how these systems work. There are hundreds of machine gun models in existence, each with its own specific firing mechanism. These guns differ in a number of other ways as well. In the next two sections, we'll look at some of the key differences between various machine gun models.

Machine Gun Feeding: Spring and Hopper System One of the main differences between different machine gun models is the loading mechanism. One popular system is the spring-operated magazine. In this system, a spring pushes cartridges in a magazine casing up into the breech. The main advantages of this mechanism are that it is reliable, lightweight and easy to use. The main disadvantage is that it can only hold a relatively small amount of ammunition.

Photo courtesy Department of Defense

A U.S. Marine training with an M16A2 5.56mm assault rifle: Assault rifles, relatively lightweight, magazine-fed automatic weapons, are the gun of choice for a wide range of ground combat scenarios.

A similar system is the ammunition hopper, such as the one used in a Gatling gun. Hoppers are just metal boxes that fit on top of the machine gun mechanism. One by one, the cartridges fall out of the hopper and into the breech. Hoppers can hold a good amount of ammunition, and they're easy to reload, but they are fairly cumbersome and only work if the gun is positioned right side up.

Mounted Machine Guns Heavy belt-fed machine guns, usually mounted on a tripod or a vehicle, may need more than one operator. Individual troops usually carry light weapons, with extendible bipods or tripods for stability. Smaller automatic guns that use cartridge magazines are classified as automatic rifles, assault rifles or submachine guns. In a general sense, the term "machine gun" describes all automatic weapons, including these smaller weapons, but it also used to describe heavy belt-fed guns specifically.

Machine Gun Feeding: Belt System For sheer volume of ammunition, the belt system is usually the best option. Ammunition belts consist of a long string of cartridges fastened together with pieces of canvas or, more often, attached by small metal links. Guns that use this sort of ammo have a feed mechanism driven by the recoil motion of the bolt. You can see how this sort of mechanism works in the diagram below.

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Top-view diagram of a common feed mechanism

The bolt (1) in this gun has a small cam roller (5) on top of it. As the bolt moves, the cam roller slides back and forth in a long, grooved feed cam piece (2). When the cam roller slides forward, it pushes the feed cam to the right against a return spring (6). When the cam roller slides backward, the spring pushes the cam back to the left. As it moves, the feed cam pivots a feed cam lever from side to side. The feed cam lever is attached to a spring-loaded pawl (8), a curved gripper that rests on top of the ammunition belt. As the cam and lever move, the pawl moves out, grabs onto a cartridge and pulls the belt through the gun. When the bolt moves forward, it pushes the next cartridge into the chamber. You can see how this works in the diagram below.

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Click and hold the trigger to see how the loading and ejection system works.

The feed system drives the ammunition belt through cartridge guides (2) just above the breech. As the bolt slides forward, the top of it pushes on the next cartridge in line. This drives the cartridge out of the belt, against the chambering ramp (3). The chambering ramp forces the cartridge down in front of the bolt. The bolt has a small extractor, which grips the base of the cartridge shell when the cartridge slides into place. As the cartridge slides in front of the bolt, it depresses the spring-loaded ejector (6). When the firing pin hits the primer, propelling the bullet down the barrel, the explosive force drives the operating rod and attached bolt backward. The extractor pulls the spent shell out of the breech. As the bolt keeps moving backward, the spring-loaded ejector pushes on the base of the shell. When the shell clears the chamber wall, the ejector springs forward, popping the shell out of the gun through the ejection port. This system lets you fire continuously without reloading. Theoretically, you could make ammunition belts of any length, so they are a great means of providing a constant supply of ammunition. The problem is that the belt is fairly cumbersome, and there's a relatively high likelihood of the feed mechanism jamming.

The Vickers MK1 belt-fed machine gun, a favorite of the British military, played a crucial role in World War I and World War II. The gun is cooled with a special water-filled jacket. As the water boils, the steam flows out to a collection can, where it condenses back into a liquid for re-use.

Photo courtesy Department of Defense

Heavier machine guns, such as this .50-caliber M-2, may be mounted on tanks, jeeps, boats and helicopters.

Gun manufacturers are continually adding new modifications to machine guns, but the basic mechanism has remained the same for more than a hundred years. Whether or not you've ever held a machine gun, or even seen one, this device has had a profound effect on your life. Machine guns have had a hand in dissolving nations, repressing revolutions, overthrowing governments and ending wars. In no uncertain terms, the machine gun is one of the most important military developments in the history of man.

STUN GUNS On the old "Star Trek" series, Captain Kirk and his crew never left the ship without their trusty phasers. One of the coolest things about these weapons was the "stun" setting. Unless things were completely out of control (as they frequently were), the Enterprise crew always stunned their adversaries, rendering them temporarily unconscious, rather than killing them.

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We're still a ways off from this futuristic weaponry, but millions of police officers, soldiers and ordinary citizens do carry real-life stun weapons to protect against personal attacks. Like the fictional phasers of "Star Trek," these devices are designed to temporarily incapacitate a person without doing any long-term damage. In this article, we'll find out how stun guns and Taser guns pull off this remarkable feat. While these weapons are by no means infallible, they can save lives in certain situations.

The Body's Electrical System We tend to think of electricity as a harmful force to our bodies. If lightning strikes you or you stick your finger in an electrical outlet, the current can maim or even kill you. But in smaller doses, electricity is harmless. In fact, it is one of the most essential elements in your body. You need electricity to do just about anything. When you want to make a sandwich, for example, your brain sends electricity down a nerve cell, toward the muscles in your arm. The electrical signal tells the nerve cell to release a neurotransmitter, a communication chemical, to the muscle cells. This tells the muscles to contract or expand in just the right way to put your sandwich together. When you pick up the sandwich, the sensitive nerve cells in your hand send an electrical message to the brain, telling you what the sandwich feels like. When you bite into it, your mouth sends signals to your brain to tell you how it tastes.

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There are a wide range of stun weapons in use today. The three most popular devices, the standard handheld stun gun, the Taser gun and the liquid stun gun, all have advantages and disadvantages.

In this way, the different parts of your body use electricity to communicate with one another.

Disrupting the System

Down for the Count!

The basic idea of a stun gun is to disrupt this communication system. Stun guns generate a highvoltage, low-amperage electrical charge. In simple terms, this means that the charge has a lot of pressure behind it, but not that much intensity. When you press the stun gun against an attacker and hold the trigger, the charge passes into the attacker's body. Since it has a fairly high voltage, the charge will pass through heavy clothing and skin. But at around 3 milliamps, the charge is not intense enough to damage the attacker's body unless it is applied for extended periods of time. It does dump a lot of confusing information into the attacker's nervous system, however. This causes a couple of things to happen: •

•

Stun-gun effectiveness varies depending on the particular gun model, the attacker's body size and his determination. It also depends on how long you keep the gun on the attacker.

If you use the gun for half a second, a painful jolt will startle the attacker. If you zap him for one or two seconds, he should experience muscle spasms and become dazed. And if you zap him for more than three seconds, he will become unbalanced and disoriented and may lose muscle control. Determined attackers with a certain physiology may keep coming despite any shock.

The charge combines with the electrical signals from the attacker's brain. This is like running an outside current into a phone line: The original signal is mixed in with random noise, making it very difficult to decipher any messages. When these lines of communication go down, the attacker has a very hard time telling his muscles to move, and he may become confused and unbalanced. He is partially paralyzed, temporarily. The current may be generated with a pulse frequency that mimics the body's own electrical signals. In this case, the current will tell the attacker's muscles to do a great deal of work in a short amount of time. But the signal doesn't direct the work toward any particular movement. The work doesn't do anything but deplete the attacker's energy reserves, leaving him too weak to move (ideally).

At its most basic, this is all there is to incapacitating a person with a stun gun -- you apply electricity to a person's muscles and nerves. And since there are muscles and nerves all over the body, it doesn't particularly matter where you hit an attacker. In the next section, we'll look at the main types of stun guns and see how they dump this charge into a person's body.

Down for the Count! Stun-gun effectiveness varies depending on the particular gun model, the attacker's body size and his determination. It also depends on how long you keep the gun on the attacker.

If you use the gun for half a second, a painful jolt will startle the attacker. If you zap him for one or two seconds, he should experience muscle spasms and become dazed. And if you zap him for more than three seconds, he will become unbalanced and disoriented and may lose muscle control. Determined attackers with a certain physiology may keep coming despite any shock

Standard Stun Gun Conventional stun guns have a fairly simple design. They are about the size of a flashlight, and they work on ordinary 9-volt batteries.

The batteries supply electricity to a circuit consisting of various electrical components. The circuitry includes multiple transformers, components that boost the voltage in the circuit, typically to between 20,000 and 150,000 volts, and reduce the amperage. It also includes a oscillator, a component that fluctuates current to produce a specific pulse pattern of electricity. This current charges a capacitor. The capacitor builds up a charge, and releases it to the electrodes, the "business end" of the circuit.

The electrodes are simply two plates of conducting metal positioned in the circuit with a gap between them. Since the electrodes are positioned along the circuit, they have a high voltage difference between them. If you fill this gap with a conductor (say, the attacker's body), the electrical pulses will try to move from one electrode the other, dumping electricity into the attacker's nervous system.

Cattle Prods Cattle prods are similar to stun guns in design -- they apply an electrical current across two electrodes -- but they serve a completely different function. A stun gun uses an electrical charge to incapacitate someone, while a cattle prod applies a charge to get a person or animal moving. A cattle prod only causes pain, it does not significantly affect the muscles and nervous system of the body.

These two devices differ mainly in voltage. The voltage in a stun gun is high enough to dump electricity into the entire body. The lower voltage in a cattle prod only shocks someone at the point of contact.

More Electrodes These days, most stun-gun models have two pairs of electrodes: an inner pair and an outer pair. The outer pair, the charge electrodes, are spaced a good distance apart, so current will only flow if you insert an outside conductor. If the current can't flow across these electrodes, it flows to the inner pair, the test electrodes. These electrodes are close enough that the electric current can leap between them. The moving current ionizes the air particles in the gap, producing a visible spark and crackling noise. This display is mainly intended as a deterrent: An attacker sees and hears the electricity and knows you're armed. Some stun guns rely on the element of surprise, rather than warning. These models are disguised as umbrellas, flashlights or other everyday objects so you can catch an attacker off guard. These sorts of stun guns are popular with ordinary citizens because they are small, easy-touse, and legal in most areas. Police and military forces, on the other hand, typically use more complex stun-gun designs, with larger ranges. In the next couple of sections, we'll look at some of these sophisticated stun guns.

Flying Tasers One popular variation on the conventional stun-gun design is the Taser gun. Taser guns work the same basic way as ordinary stun guns, except the two charge electrodes aren't permanently joined to the housing. Instead, they are positioned at the ends of long conductive wires, attached to the gun's electrical circuit. Pulling the trigger breaks open a compressed gas cartridge inside the gun. The expanding gas builds pressure behind the electrodes, launching them through the air, the attached wires trailing behind. (This is the same basic firing mechanism as in a BB gun.)

The electrodes are affixed with small barbs so that they will grab onto an attacker's clothing. When the electrodes are attached, the current travels down the wires into the attacker, stunning him in the same way as a conventional stun gun. The main advantage of this design is that you can stun attackers from a greater distance (typically 15 to 20 feet / 4 to 6 meters). The disadvantage is that you only get one shot -- you have to wind up and re-pack the electrode wires, as well as load a new gas cartridge, each time you fire. Most Taser models also have ordinary stun-gun electrodes, in case the Taser electrodes miss the target. Some Taser guns have a built in shooter-identification system. When a police officer fires the Taser electrodes, the gun releases dozens of confetti-sized identification tags. These tags tell investigators which gun was fired, at what location. Some Taser guns also have a computer system that records the time and of every shot. Tasers are only one way to conduct current over greater distances. In the next section, we'll look a relatively new long-range stun weapon that doesn't use any wires at all.

Stun Abuse The companies that make stun guns specify that the weapons should be used conservatively, only for self-defense or incapacitating an unruly person. Unfortunately, stun guns are commonly used as torture devices in many parts of the world.

Amnesty International reports that a number of governments routinely use stun weapons to extract confessions from political prisoners. These officials know that electrical torture leaves less evidence than many other methods. The shock from a stun weapon is extremely painful, but it doesn't leave an obvious wound. So, while stun guns might be relatively safe weapons when used correctly, they can be quite dangerous in the wrong hands.

Liquid Charge

One of the newer stun weapons is the liquid stun gun. These devices work the same way as Taser guns except they use a liquid stream to conduct electricity rather than extended wires.

The gun is hooked up to a tank of highly conductive liquid, typically a mixture of water, salt and various other conductive elements. When you pull the trigger, electrical current travels from the gun, through the liquid stream, to the attacker. These guns have a longer firing range than Taser guns, and you can shoot them many times in succession. They are generally more cumbersome than Taser guns, however, because you need to cart the conductive liquid around. High-powered guns work with vehiclemounted water cannons, while portable models typically include a water tank backpack. Many portable units use the same sort of water pumping system as Super Soaker squirt guns. Today, stun weaponry is a rapidly growing field of invention. Law enforcement and military forces need non-lethal weapons to subdue angry mobs without racking up civilian casualties. Many citizens who are concerned for their safety but aren't comfortable with firearms are seeking out reliable "safe weapons." As this technology advances, the prospect of Star Trektype phasers doesn't seem so far-fetched. The teleporter, however, is another story...

Stun Belt In addition to incapacitating violent citizens out on the street, stun technology is also used to subdue criminals behind bars. There are prisons around the world that use stun-belt devices to keep their inmates in line, and to intimidate them.

Stun belts are basically stun guns that are already attached to potential offenders. Corrections officers carry a remote-control unit that operates the stun weapon. If an inmate becomes unruly, the officers activate the belt, which applies a high-voltage charge to the inmate's kidneys. While the inmate is stunned, officers may drag him back to his cell.